Mattress foundation



FIG. 1 is a perspective view of a mattress foundation according to my new design.

FIG. 2 is a top view of the mattress foundation;

FIG. 3 is an end view of the mattress foundation, the opposite end being a mirror image thereof;

FIG. 4 is a side view of the mattress foundation, the opposite side being a mirror image thereof; and,

FIG. 5 is a bottom view of the mattress foundation.

The dotted lines shown in the drawings depict portions of the mattress foundation that form no part of the claimed design. 

CLAIM The ornamental design for a mattress foundation, as shown and described. 